The invention relates to fluid seals and packings which have particular application to a high pressure rod or a stem seal. The prior art include O-rings and other squeeze packings, compression packings and seals, face seals and pressure-energized seals of various types.
The apparatus in accordance with the invention may be used in place of conventional compression packings and seals as well as other sealing apparatus. In a conventional compression seal a material such as aluminum, copper, lead foil, TFE elastomers, leather, flax, cotton, flexible graphite, plastics or asbestos, is stacked or packed into an annular cavity and a seal against a rod or stem element is achieved. This seal is obtained, at least in part, due to the compression imposed by the cooperating housing members or the fluid pressures which are contained by the seal. At high pressures, presently available packing elements tend to become a solid mass once their internal shear resistance is exceeded by the contained pressure. Thus, the packing or packing set responds as one seal with no backup or secondary sealing ability.
It is an object of the invention to provide a seal assembly which, at least in some embodiments of the invention, provides true seal redundancy.
It is another object of the invention to provide a seal assembly which will positively seal even at high pressures.